In radio communication, particularly, in wideband transmission, there is a path that allows a radio wave to travel therethrough and arrives early. There is also a path that includes objects, such as buildings or mountains, which reflect and thus delay a radio wave in the arrival thereof. An environment where there are a plurality of paths is referred to as a multi-path environment. OFDM (Orthogonal Frequency Division Multiplexing) has recently gained attention as a method to implement high-speed and high-reliability transmission under the multi-path environment, and is adopted in a variety of fields including next generation mobile communication systems, radio LAN, and broadcasting. In a case that a receiver apparatus demodulates an OFDM signal, channel estimation is performed to calculate a channel frequency response (CFR) of a channel on each sub-carrier. To this end, in one method, a transmitter apparatus transmits to a receiver apparatus a pilot symbol. The waveform (or a signal sequence) of the pilot symbol is stored on the receiver apparatus. In order to perform high-precision channel estimation using the pilot symbol, accurate frequency correlation is needed.
Non Patent Literature 1 describes a technique of estimating a frequency response in accordance with MMSE (Minimum Mean Square Error) criterion in a standard pilot OFDM. More specifically, in accordance with Non Patent Literature 1, PDP (Power Delay Profile) is modeled, a frequency correlation is determined from the modeled PDP, and the channel estimation is performed on the MMSE criterion using the frequency response.